In the prior art various window guards have been disclosed including those in the following U.S. patents:
U.S. Pat. No. 1,662,167 granted to O. M. Rexinger on Mar. 13, 1928, disclosed an expansible grating window guard with side members in the form of channels with out-turned legs;
U.S. Pat. No. 1,854,153 granted to W. W. Ammen on Apr. 12, 1932, disclosed a removable window guard which can be locked in place and which shields the attachment bolts;
U.S. Pat. No. 1,902,949 granted to J. P. Condon on Mar. 28, 1933, disclosed a window guard with a channel frame and means for detachably locking it in place in a window.
U.S. Pat. No. 3,738,062 granted to H. A. Ughi on June 12, 1973, discloses a telescoping frame, hinged to a window and lockable in place with evidently some limitation of access to the fastener.
From these prior art patents it can be seen that an easily installed, low-cost, high protection, securely lockable but simply and instantly jettisonable window guard or the like which provides full access, would be highly desirable.